The F-22 Raptor is the only US fighter
design with the stealth, speed and agility to defeat the new Russian
PAK-FA design. To be highly effective against the PAK-FA, it will need
a range of upgrades, including a new technology infrared sensor.
Depicted technicians at the USAF AEDC performing low observables
testing on an electro-optical sensor fairing, developed for the AIRST
sensor. The AIRST was deleted from the F-22 avionic suite during
development as a cost saving measure (US Air Force image).

Imagine
an apocryphal story of three fighter pilots meeting in the bar at an
air combat
conference in Stockholm, in the year 2015. Chuck is a NATO F-22A
Raptor pilot based in Germany, Boris
an Su-35-1 Flanker E Plus pilot flying from one of the bases protecting
Moscow,
and Johan, a F-35A Lightning II pilot from the Netherlands. All
are masters of their craft and
after drinks, “merely to lubricate the vocal chords”, they do what
fighter
pilots all over the world do – swap stories and make claims about their
beloved aircraft.

Chuck
starts.“I’m king of the skies,”
he claims. “I supercruise at 52,000 feet and Mach 1.7.Boris, I can see you from ~100 nm, and
my AIM-120D launch range at this Mach is 70 nm.You
are
one
dead
Flanker.”Boris acknowledges
the performance of the APG-77 and the
Raptor, but replies, “Your missiles are easy to avoid.When you fire, my OLS-35 will see the
flare, and I will turn away to out-run the missile.You need to fire closer than 50 nm – even then at
50,000 feet and Mach 1.2, my Flanker can out-turn your missile.If you are side or rear on I can get a
lock-on at ~40 nm and I have a choice of seeker heads, so you might
wear an
R-77M in the backside.”“No way
Boris,” Chuck replies, “I know that game. I’m head on and you can’t see
me
until about ~15 nm. If I have not killed you at 50 nautical, I’m outa
there at
the speed of heat.” Boris and Chuck concede that there might be a
nil-all draw,
with Chuck being untouchable because of the Raptor’s stealth, altitude
and
speed and the well defended Su-35-1 defeating the Raptor’s missiles [1].

Now
Boris
makes
his
point.“Comrade Johan, I
have something special for you.My
IRBIS-E will see you head-on at ~25nm, but I fly my boys very wide and
share
the paints on our digital network.At side
and rear looks, I see you at ~45 nm and my ramjet
RVV-AE-PDs can
get you at that range.”“No way”,
Johan responds, “my APG-81 radar will see you at ~75 nm and I can
launch at 50
nm.If you fire, my DAS will see
the missile at launch, so I’ll turn away to break lock”.“And my wingman will see you in the
turn, computer network will still know where you are, and we will
skewer you in
the cross-fire” is Boris’s riposte, “and you will run out of missiles
before I
do,If I duck your AIM-120D shots,
I will win easily”.They bicker
about the strengths of their own aircraft and weaknesses of the other’s
and Johan
grudgingly agrees the Flanker might be the winner.

Chuck
and
Johan
stay
in
the
bar
after Boris is unexpectedly ‘called away’ by men
in dark
coats, and agree that work needs to be done on improving the AIM-120D’s
terminal lethality.

Essentially,
this
is
a
deadly
play
between stealth, agility, sensors and missiles.From
the front quarter the Raptor’s 0.0001
square meter Radar Cross Section (RCS) and the Lightning II’s 0.001
square
metres make them difficult targets.The
Flanker-E Plus, while having a reduced radar
signature, still has a
residual RCS of about 2 square metres, such that the F-22A and the F-35
will
see the Su-35-1 way beyond their missile launch range.The Su-35-1 struggles to see the F-22A
on radar, but can find the F-35’s 0.01 square metre lower side and rear
RCS.The AIM-120D is a fine
missile, but the Su-35-1 has finer defences, so the missile kill
probabilities
are likely to be low.When out of
missiles, the F-22 Raptor can escape.The
F-35 Lightning II cannot.

A
more
likely future scenario is that Boris will be banned from subsequent air
combat
conferences, so we must rely on more conventional air combat operations
analyses.If we move forward just
a couple of years, say to the year 2017, and the PAK-FA is operational,
there
is a profound change in air combat engagements.

Suppose
the
Russians
don’t
quite
master
stealth to the degree of the F-22A, but
manage
a RCS of 0.01 square metres from all aspects.The
F-22A’s
APG-77
will
detect
the
PAK-FA at ~40 nm and the
F-35’s APG-81 at ~30 nm. Passive electronic surveillance might increase
detection ranges, but this still makes long-range missile shots
problematic, as
tracking depends upon the opponent emitting, which smart opponents will
try not
to do.

The
PAK-FA’s
radar
can
be
expected
to be an improvement on the IRBIS-E so
at
front-on aspects might detect the F-22A at ~15 nautical miles and the
F-35 at ~28
nautical miles; and from side and rear aspects, the F-22A at ~43
nautical miles
and the F-35 at ~51 nautical miles.

Infrared
sensors
are
the
next
growth
area in air combat. Every air combat jet
has
unavoidable infrared signatures – converting kerosene into thrust at
prodigious rates does that. The existing OLS-35, developed for the
Su-35BM, is
credited with the ability to detect a ‘fighter type’ target head on
from 27
nautical miles, and from behind at around 50 nautical miles, through a
90°
sector. It uses conventional detector
technology, and provides similar performance to the Eurofighter Typhoon
PIRATE
infrared sensor. It is likely the PAK-FA will have infrared signature
management as is found on the designs of the YF-23A, B-2A and the
F-22A, but
not on the F-35 [2].

The
emerging
technology
of
Quantum
Well
Imaging Photodetectors (QWIP) is
set to
cause an upset in this market sector.

Quantum Well Imaging Photodetectors

Advances in QWIP technology single chip
imagers will see a new generation of infrared sensors deploy over the
next decade. Not limited in infrared colour sensitivity like legacy
bandgap imagers, QWIP imagers offer the potential to detect cooler
targets are greater distances, and provide the high resolution required
for standoff identification of targets. Above 10.2 micron band 10242
pixel longwave image produced by a US Army Research Lab / L-3
Cincinnati corrugated QWIP [no image enhancement applied], depicted
below. QWIP technology is now available in the US, EU and Russia
(Images refer Choi and Forrai, Corrugated quantum-well IR
photodetectors see light in higher definition, 16 September 2008, SPIE
Newsroom.
DOI:
10.1117/2.1200808.1237.).

QWIP
based
imaging
Infra
Red
Search
and Track (IRST) detectors can be
“tuned” by
design for sensitivity in a particular infrared band, using a
fundamentally
different detection technique to conventional “band gap” detectors
where the
material determines the colour sensitivity of the detector. First
commercialised by Germany’s AIM/Diehl-BGT, QWIPs have since been
adapted for
ballistic missile defence applications. QWIPs have also been built to
operate
not only in the “conventional” midwave and longwave infrared bands, but
also in
the “very longwave” 15 micron band to detect very cool targets. QWIPs
capable
of simultaneously imaging in two, three or four infrared bands have
also been
manufactured and marketed. QWIP technology, therefore, opens up the
potential
for even greater detection ranges against targets cooler than what
current
production infrared sensors can track, and provide for much better
infrared
background rejection.

Consider
a
QWIP
technology
“OLS-50M”
installed
in the PAK-FA.Such
a device could be design-optimised for simultaneous
detection
and tracking of aircraft exhausts, jet-plumes and missile flares to
ranges of
70 nm and beyond – the limiting factors are the size of the optics,
cooling system and detector area.Russia
has decades of experience in the integration of
infrared sensors
into its weapons systems, and QWIPs could well become the primary
sensor and
radar the secondary.This means
that the F-22A AN/ALR-94 will be denied signals to detect and track the
PAK-FA.

The
‘shooting
match’
shifts
from
radar-centric
to ‘infrared centric’.The
problem
here is that the PAK-FA
will have it, the F-22A does not, and the ability of the F-35 EOTS and
DAS to
make long range aircraft detections and guide weapons is at best
‘unproven’.The F-35 systems have not been
designed
to be highly sensitive at the task of searching and tracking distant
aircraft
at those infrared colours where aircraft and their jet engines emit
most of
their infrared energy.An
understanding of the physics, or for the ever-hopeful, a simple
Developmental
Test and Evaluation exercise will demonstrate this.

With
the
Beyond-Visual-Range
(BVR)
radar
detections
being
reduced to distances
below 60
nautical miles and infrared sensor detection ranges growing beyond 50
nautical
miles, a new generation of missiles will be required to dominate the
battlespace.

Russian
missile
companies
have
shown
much
more flexibility and adaptability in
the
design of missiles, so the PAK-FA could have a new-generation of
shorter range,
but higher agility missiles – a fusion of the ideas in the R-74 and
R-77M, with a diverse mix of seeker heads. These missiles will likely
be cued
by the IRST sensor, be equipped with inertial midcourse guidance and,
probably,
mid-course guidance update capability transmitted either by radio, or
possibly infra-red laser or millimetric
wave links.

Expect
the
PAK-FA
to
have
vectored
thrust and high levels of agility like the
Flankers
it is to either replace or complement. Long missile range requires
large rocket
or ram-jet motors and these heavy weapons lack the agility to pull high
terminal ‘G’, and may be ‘ducked’ by the PAK-FA as easily as by the
Su-35-1.

The
PAK-FA
will
use
a
new
super-cruising engine, based on technology from
the
Al-41F series, so its tactic might be to maintain combat speeds of
about Mach
1.5 and use a more compact version of the ramjet RVV-AE-PD.A supersonic launch enables a ramjet to
light without a powerful booster – thereby denying an opponent the
detection of the usual missile launch flare.

Fights
between
the
F-22A
and
the
PAK-FA will be close, high, fast and lethal.The
F-22A
may get ‘first look’ with the
APG-77, the Advanced Infra Red Search and Track (AIRST) sensor having
been
deleted to save money, but the PAK-FA may get ‘first look’ using its
advanced
infrared sensor. Then, the
engagement becomes a supersonic equivalent of the Battle of Britain or
air
combat over North Korea.The
outcome will be difficult to predict as it will depend a lot on the
combat
skills of the pilots and the capabilities of the missiles for end-game
kills.
There is no guarantee that the F-22 will prevail every time.

The
fate
of
the
F-35
Lightning
II
would be far worse in an air combat
environment
challenged by the PAK-FA.If the
Mach 1.5 PAK-FA is using its infrared sensor as the primary sensor and
observes
radio frequency emission control (EMCON), then the first detection by
the
F-35’s APG-81 radar could be at ~20 nautical miles or less with a
missile
launched by the PAK-FA’s infrared sensors already inbound from 60 to 70
nautical miles away.The PAK-FA
could easily break to a direction outside the F-35’s AIM-120 engagement
zone.

The
sustained
turning
performance
of
the
F-35A Lightning II was recently
disclosed
as 4.95 G at Mach 0.8 and 15,000 ft.A
1969
F-4E
Phantom II could sustain 5.5 Gs at 0.8 Mach with 40 percent internal
fuel at 20,000 feet. The F-35 is also much slower
than the 1960s F-4E or F-105D. So the F-35A’s aerodynamic performance
is
‘retrograde’ when compared with 1960s legacy fighters.The consequence of such inferior JSF
performance is that its DAS might detect an incoming missile, but the
aircraft
lacks the turn-rate to out-fly it. As
the F-35 also lacks the performance to engage or escape, repeated
‘freebie’ shots from the PAK-FA could inflict high losses.Expect the exchange rate to be of the
order of 4:1 in favour of the PAK-FA, possibly much higher[3].

Russian
aerospace
companies
have
demonstrated
an
ability to outpace US
aerospace
manufacturers in terms of delivery of an operational capability and
also the
diversity of the capabilities of their weapons systems. The cumbersome
US
acquisition system, and marketing rather than technology driven
aerospace
industry, put the US at a distinct competitive disadvantage in rapidly
adapting
to an evolving threat environment.

The
most
dangerous
situation
the
US
could
face, is where the high and upwardly spiralling
development and production costs of the JSF ‘cuckoo’ the available
resources,
which are needed to develop the advanced capabilities necessary to
counter the
new Russian PAK-FA, and the generation of new weapons which the PAK-FA
will
inevitably be armed with.

Complacency
is
not
an
option.Having ruled the
roost for the decade out to 2015, the F-22A may be knocked off its
perch by a
newcomer, unless the US invests in new sensors, especially, and
advanced
technology Infra-Red Search and Track, stealth improvements and a new
generation of missiles for the F-22 – assuming it even builds more than
the token number of F-22s currently planned. The F-35 has already been
neutralised
and negated by the Su-35-1/35BM and will be substantively overmatched
by the
PAK-FA. The West needs to think long, hard and fast about the PAK-FA,
as the
current and retrograde “F-35 centric” future fighter fleet model
guarantees certain
defeat in future combat.

PAK-FA rendering by NPO Saturn. Unlike the
JSF, the stealthy PAK-FA is
being designed with air superiority performance and high agility as the
primary consideration. To date only speculative renderings have been
released, making assessments difficult (Saturn NPO).

[3]
Boeing F-15SE ‘Silent Eagle’.This
low-signature version of the F-15 Eagle was assessed during the
compilation of
this NOTAM.Its radar cross
section, while claimed to be comparable to the export configuration of
the F-35
from nose-on is likely to be substantially inferior from other aspects.Its infrared signature will be similar
to the standard F-15 Eagle.Thus,
the PAK-FA using radar will detect the Silent Eagle at a range
sufficient to
launch BVR missiles and at similar or greater ranges to the F-35 for
infrared-based engagements.Flying
wide sweeps and distributing sensor detections as is done for the
legacy
Sukhois will enhance radar detections and enable IRST ranging. The
advantage the
F-15SE Silent Eagle has over the F-35 JSF is that it has the
aerodynamic
performance and fuel reserves to egress from a dangerous air combat
engagement.